Cellular communication networks evolve towards higher data rates, improved capacity and improved coverage. In the 3rd Generation Partnership Project (3GPP) standardization body, several technologies have been and are also currently being developed.
LTE (Long Term Evolution) is an example of a standardised technology. In LTE, an access technology based on OFDM (Orthogonal Frequency Division Multiplexing) is used for the downlink, and Single Carrier FDMA (SC-FDMA) for the uplink. The resource allocation to wireless terminals, also known as user equipment, UEs, on both downlink and uplink is generally performed adaptively using fast scheduling, taking into account the instantaneous traffic pattern and radio propagation characteristics of each wireless terminal. One type of data over LTE is audio data, e.g. for a voice conversation or streaming audio.
To improve the performance of low bitrate speech and audio coding, it is known to exploit a-priori knowledge about the signal characteristics and employ signal modelling. With more complex signals, several coding models, or coding modes, may be used for different parts of the signals. These coding modes may also involve different strategies for handling channel errors and lost packages. It is beneficial to select the appropriate coding mode at any one time.